Declining reservoir pressure in natural gas wells may lead to gas production decreases. The typical cause of this decrease is liquid loading that occurs when water and condensate enter the bottom of the well. Foaming agents (sometimes referred to as “foamers”) are frequently used to aid in the unloading of water and condensate accumulated in the wellbore, thereby increasing production from a loaded well. Such agents are generally applied either by batch treatments or continuous applications via injecting down a capillary string or via the casing/tubing annulus. Foamers function by reducing the surface tension and fluid density in the wellbore, and may also be used in conjunction with a lift gas to enhance oil recovery from oil wells.
U.S. Pat. App. Pub. No. 2006/0128990 teaches a method of treating a gas well comprising a chloride-free amphoteric surfactant. U.S. Pat. No. 7,122,509 discloses a method of preparing a foamer composition having an anionic surfactant and a neutralizing amine. In U.S. Pat. App. Pub. 2005/0137114 an aqueous foaming composition comprising an anionic surfactant, a cationic surfactant, and a zwitterionic compound is disclosed. PCT App. Pub. No. WO 02/092963 and U.S. Pat. App. Pub. No. 2007/0079963 disclose methods for recovering oil from a gas-lifted oil well using a lift gas and a foaming surfactant which consists of nonionic surfactants, anionic surfactants, betaines, and siloxanes.
While such foamers represent a significant contribution to the art of unloading fluids in oil and gas wells, there still remains a need for improved foamers and methods of using improved foamers. It is thus an objective of this invention to provide a cost-effective foamer for unloading oil, water, or mixtures thereof from oil and/or gas wells. Such improved foamers would also ideally be compatible with anti-corrosive and anti-scale agents.